1. Field of the Invention
The present invention relates to a light-emitting module. The light-emitting module may be rigid or flexible.
2. Description of Related Art
Utilization of light-emitting module is diversified, for example, the light-emitting module may be applied to a display to function as a backlight module. 97% of the backlights utilized in liquid crystal displays (LCDs) of personal computer in the market are cold cathode fluorescent lamps (CCFLs). Light-emitting diodes (LEDs) are mainly applied to displays with sizes less than 7 inches, and application of the LEDs on large size LCDs is still under development. Since the LEDs for RGB have been applied to LCD televisions (TV), and have the advantages of wide color gamut, environmental protection, long lifespan, fast response, high dynamic contrast etc., conventional CCFL backlight may be gradually substituted by LED backlight. As to a LCD TV, an edge-emitting RGB LED backlight module is applied to LCD panel thereof, in which a light guide plate is required to convert a line light source into a planar light source, and therefore loss of light is relatively large, and it is not suitable for a large size TV panel. Correspondingly, a direct-under type LED may satisfy a requirement of the large sized TV panel.
FIG. 1 is a perspective view of a conventional LCD. Referring to FIG. 1, the LCD 10 equipped with a backlight module includes a flexible board 11, a backlight conductor 12, a rod light transmitter 13, a LCD panel 14, a spur 15 and a LED 16, wherein the LED 16 is the edge-emitting LED, and may be converted to a planar light source via the backlight transmitter 12 and the rod light transmitter 13 for providing the light source to the LCD panel 14. The LED 16 is set as an edge-emitting structure via the spur 15 to reduce thickness of the display, though a light-emitting efficiency thereof is relatively low.
Since light emitting of a LED chip is non-directional, front light emitting amount of the LED chip is limited. Further additionally, due to an absorption effect of a LED substrate, loss of light within the LED due to internal light absorption is relatively great, and in terms of external, the light-emitting efficiency thereof is rather low. Presently, most manufactures try to improve the light-emitting efficiency and reduce light absorption of the LED substrate, and a method thereof is utilizing a substrate transfer technique or coating a mirror layer on the LED substrate. Moreover, to improve a heat-dissipating efficiency of the LED, thermal substrate or coating of thermal paste are generally utilized, however, the thermal effect thereof is limited. As to a large sized luminescent panel, since the large size luminescent panel is manually arranged in an array, productivity thereof is relatively low, and man-power cost is relatively high.
In addition, in one of the conventional techniques, light emitted from the LED may be reflected and guided into a light pipe. This technique belongs to the edge-emitting LED backlight source, by which reflection effect and light-emitting volume of the LED may be improved based on adjustment of whole structure thereof and association with other devices. Another conventional technique belongs to a lamp edge-emitting backlight source including a lamp, a light guide plate, a diffusion plate, a prism sheet, and a reflection sheet. In this technique, the reflection sheet is applied for preventing scratches on backside of the light guide plate, and improving the front light-emitting volume of the backlight source. The advantage of this conventional technique is that fabrication method thereof is relatively mature, and integration of components therein is relatively easy. The reflection sheet is used for compensating the loss of light occurred during incidence of the light into the light guide plate, so as to improve the front light-emitting volume of the backlight source.
Therefore, how to improve the light-emitting efficiency, the heat-dissipating efficiency, and to thin the light-emitting module to achieve the flexible effect is still an issue under development.